Colours disappear when exporting to Blend4Web
The problem is that your .blend is using .tga and .tif files, which are not supported in Blend4Web (since they are not web-friendly formats).

If you convert these to .png (or .jpg where lossy is acceptable) you should be fine. This will also cut your file sizes down drastically and probably even improve your Viewport performance within Blender. Remember that since your delivery platform is a web browser, smaller and lower-res images are better whenever possible.

Another issue I noticed (unrelated to images) is that you'll need to either scale down your model or increase the clipping distance.